WO2003097771A1 - Adsorption desulfurization agent for desulfurizing petroleum fraction and desulfurization method using the same - Google Patents

Abstract

An desulfurization method for a light oil which comprises a step of removing sulfur compounds in an light oil fraction by the adsorption with an adsorption desulfurization agent comprising a fibrous active carbon provided in an adsorption tower (1), and a desorption and regeneration step of washing the resulting adsorption desulfurization agent with an aromatic solvent to regenerate the desulfurization agent. The method allows the production of a light oil being satisfactorily freed of sulfur at a relatively low equipment and operation costs over a long period of time, and in the method, difficult-to-remove sulfur compounds, such as 4, 6-DMDBT, and multi-ring aromatic compounds having two or more rings are selectively removed.

Description

 Specification

 TECHNICAL FIELD The present invention relates to an adsorption desulfurizing agent for desulfurizing a petroleum fraction and a desulfurization method using the same.

 The present invention relates to an adsorptive desulfurization agent for adsorptive removal of sulfur compounds contained in petroleum fractions, particularly gas oil fractions, which become petroleum liquid fuel oils, a method for producing gas oil using the adsorptive desulfurization agent, and a method for producing the same. The present invention relates to light oil produced by the production method. Background art

Enters the 2 1 century, both in terms of the reduction of vehicle emissions of environmentally friendly and N 0 X such decrease emissions cut of CO ₂ gas is greenhouse gas, sulfur contained in the fuel Is required to be further reduced. In the near future, the sulfur content of gasoline and diesel is expected to be regulated to less than 10 ppm. In addition, with the spread of fuel cells such as automobiles equipped with on-port reformed fuel cells, petroleum-based liquid fuel oil with a lower sulfur content may be required. Therefore, the desulfurization technology required to obtain petroleum-based liquid fuel oil with ultra-low sulfur content is now being actively studied. Conventionally, a hydrodesulfurization method has been mainly used as a gas oil desulfurization technique. However, in order to desulfurize gas oil to a low sulfur concentration of 15 ppm or less using the hydrodesulfurization method, it is necessary to raise the reaction temperature, and raising the reaction temperature causes a problem that the hue of the product gas oil deteriorates. . As a method for improving the problem of the hue of light oil, a method of contacting a light oil fraction having deteriorated hue with activated carbon has been proposed (for example, Japanese Patent Application Laid-Open No. Hei 6-136370, No. 11-118). Page 2, JP-A-2000-192504, pages 3-6). Also, a method of decolorizing light oil by performing a hydrogenation treatment in the presence of a crystalline aluminate-containing inorganic oxide catalyst or activated carbon catalyst supporting one or both of metals VI and III. (For example, see Japanese Patent Application Laid-Open No. 2000-280209, pp. 2-4). In addition, various processes have been developed for desulfurization technologies other than the hydrodesulfurization method. For example, there is an example of using a sulfur compound adsorbent in which a copper component is supported on an alumina carrier in order to remove a trace amount of a sulfur compound contained in a hydrocarbon oil (for example, Japanese Patent No. 3324746, (See pages 2-4). By the hydrodesulfurization method, difficult-to-desulfurize compounds such as 4-methyldibenzothienephene (4-MDBT) and 4,6-dimethyldibenzothienephene (4,6-DMDBT) remaining in the gas oil fraction are removed. An enormous amount of catalyst and hydrogen is required to remove the sulfur to below 15 ppm. In particular, hydrogen is expensive and affects the price of refined gas oil. In addition, research on various processes for the desulfurization of gas oil fractions has been conducted, but these are still at the bench equipment level, and currently there is no choice but to add one reactor. Therefore, in order to reduce the sulfur content of the gas oil fraction, there is a need for innovative technology that can desulfurize with simple equipment and low operating costs. Recently, a technique for reducing polycyclic aromatics (PAH's) contained in diesel exhaust gas has also been required. In other words, gas oil with extremely low sulfur content and PAH'S has the potential to contribute greatly to society in terms of preventing air pollution in large cities and protecting the global environment. Disclosure of the invention

The present invention solves the above-mentioned problems of the prior art. The first object of the present invention is to reduce the sulfur content from a petroleum fraction sufficiently, particularly 10 ppm or less, with relatively low equipment costs and operation costs. And a method for desulfurizing a petroleum fraction using the adsorptive desulfurizing agent. A second object of the present invention is to provide a production method for producing a gas oil having a reduced PAH'S as well as a sulfur content. Further, a third object of the present invention is to provide an adsorptive desulfurizing agent capable of selectively removing difficult-to-desulfurize compounds such as 4,6-DM DBT from a petroleum fraction, and a method for producing gas oil using the same. It is in. According to a first aspect of the present invention, there is provided an adsorptive desulfurizing agent comprising a carbon material having a specific surface area of 500 m ² / g or more and adsorbing an organic sulfur compound contained in a petroleum fraction. A desulfurizing agent is provided. In the desulfurization process of petroleum fraction, the present inventor used an adsorbent desulfurizing agent composed of a carbon material having a specific surface area of 500 cm ² / g or more in place of the hydrodesulfurization catalyst, and — Selective removal of difficult-to-desulfurize compounds such as DM DBT, resulting in the reduction of sulfur in petroleum fractions to extremely low levels of less than 10 ppm. Furthermore, it has been found that the adsorptive desulfurization agent of the present invention can selectively adsorb PAH'S and can significantly reduce the concentration of PAH, S in a petroleum fraction. In the adsorption desulfurization agent of the present invention, the specific surface area of 1000 m ² / g or more carbon materials, especially 20 00m ² / g or more and an average length 100 xm or more, more preferable to use the above fiber維状activated carbon 1 mm I like it. When fibrous activated carbon is used as the adsorptive desulfurizing agent, since the fibrous activated carbon has fibrous pores extending in the radial direction, the adsorption capacity can be further increased. In particular, fibrous activated carbon having a large amount of mesopores having a pore radius of 10 A or more is preferably used because of its high adsorption rate. Since the adsorptive desulfurization according to the present invention is mainly physical adsorption, it can be carried out in a liquid phase and at a lower temperature, preferably at 100 ° C. or lower. Further, the fibrous activated carbon is suitable from the viewpoint of operation because it hardly flows out of the adsorption tank (tower) and has little fluctuation in the differential pressure in the adsorption tank. Further, the present inventor focused on the micropore specific surface area and the mesopore average pore size as parameters of the adsorptive desulfurization agent affecting the desulfurization characteristics, and the value of the product of both, S mi cr ox 2 x V ex tZS ext Is more than 3.0 cm ³ / g, and more than 5. Ocrr ^ Zg, it was found that the adsorptivity was significantly improved. Activated carbon, inorganic porous materials such as zeolites and alumina, metals such as nickel, and composites thereof are known as adsorption desulfurizing agents for sulfur compounds such as hydrogen sulfide. Conventionally, activated carbon has a low sulfur compound adsorption capacity and is sufficient as an adsorbent desulfurizer. Was considered to have no significant performance. In particular, in the gas field, the mainstream is Zelite Light. The present inventor studied various types of materials for adsorptive desulfurization of petroleum fractions. As a result, carbon materials having a specific specific surface area, particularly fibrous activated carbon, were converted to organic sulfur compounds, in particular, Found that it has excellent adsorptive desulfurization performance for benzothiene phenes and dibenzothiene phenes. Further, in the adsorptive desulfurizing agent of the present invention, the petroleum fraction to be brought into contact with the adsorptive desulfurizing agent preferably contains a hydrocarbon having a boiling point of 30 to 400 ° C. as a main component. It is preferably at most 0 ppm. When the petroleum fraction is a gasoline fraction, the adsorptive desulfurizing agent preferably further contains a zeolite component. According to a second aspect of the present invention, there is provided a method for desulfurizing a petroleum fraction, comprising: an adsorptive desulfurizing agent containing a carbon material having a specific surface area of 50 Om ² Zg or more; and a petroleum fraction containing an organic sulfur compound. And a method for desulfurizing a petroleum fraction including a step of contacting the oil fraction with a petroleum fraction. In the desulfurization method of the present invention, it is preferable that the petroleum fraction is brought into contact with the adsorptive desulfurizing agent in a liquid phase, and in particular, the adsorbent desulfurizing agent and the petroleum fraction at a temperature of 100 ° C or lower. Is preferably contacted. When the petroleum fraction is a gasoline fraction, the adsorptive desulfurizing agent preferably further contains a zeolite component. In the desulfurization method of the present invention, after the desulfurization agent is brought into contact with a petroleum fraction to desulfurize, the adsorbent desulfurization agent is heated in a non-oxidizing atmosphere to desorb the organic sulfur compound and to remove the adsorption / desorption sulfurizer. It is preferable to include a step of regenerating, and a step of bringing the regenerated adsorptive desulfurizing agent into contact with a petroleum fraction containing an organic sulfur compound. The adsorptive desulfurization agent after adsorptive desulfurization should be easily desorbed and regenerated by washing with a solvent such as toluene, alcohol, and acetone, heating under a nitrogen atmosphere, and heating under reduced pressure, and used repeatedly. Is possible. In particular, by heating under a non-oxidizing atmosphere (usually under a nitrogen atmosphere) and / or under reduced pressure, sufficient regeneration is possible in a short time. is there. Although it does not function directly as a desorbent, water or steam can be used as a heating source. According to a third aspect of the present invention, there is provided a method for producing a gas oil, which comprises converting a gas oil fraction in a liquid phase having a sulfur content of 500 ppm or less into a carbon material having a specific surface area of 50 O m ² / g or more. A gas oil comprising: an adsorption desulfurization step of contacting with an adsorption desulfurization agent that adsorbs sulfur compounds contained in the gas oil fraction; and a desorption regeneration step of washing and regenerating the adsorption desulfurization agent with an aromatic solvent. Is provided. According to a fourth aspect of the present invention, the sulfur concentration obtained by the production method of the present invention is 15 ppm or less, and the ratio of sulfur of 4,6-dimethyldibenzothienephene to total sulfur is 1%. 0% or less and 90% distilling temperature is 310 ° C or more, light oil, sulfur concentration is 15ppm or less, and the ratio of two or more ring aromatics to total aromatics is 7% % Or less and a 90% distillate concentration of 310 ° C. or higher, or a sulfur concentration of 15 ppm or less, and a ratio of tricyclic aromatics to total aromatics of 0. Gas oil having a distilling temperature of less than 5% and a 90% distillation temperature of 310 ° C or more is provided. BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a diagram showing an example of an apparatus used in the gas oil production process of the present invention. FIG. 2 is a view showing an apparatus used in the gas oil production process of the present invention and steps 1 to 3 using the apparatus.

 FIG. 3 is a diagram showing an apparatus used in the gas oil production process of the present invention and steps 4 to 6 using the apparatus.

 FIG. 4 is a diagram showing characteristics of the adsorption amounts of various adsorbents prepared in Example 1. FIG. 5 is a diagram showing changes in the concentration of light oil and sulfur content flowing out of the column when the raw gas oil was passed through the column in Example 2.

 FIG. 6 is a diagram showing changes in the concentrations of light oil and n-decane flowing out of the column when light oil in the column was discharged with n-decane in Example 2.

FIG. 7 shows that n-decane and sulfur in the column were eluted with toluene in Example 2. FIG. 5 is a graph showing changes in the concentration of the desorbent, n-decane and sulfur content flowing out of the column at the same time.

 FIG. 8 is a diagram showing the change in the concentration of light oil and sulfur content flowing out of the column when the raw gas oil is passed again in Example 2.

 FIG. 9 is a diagram showing the types and concentrations of sulfur compounds contained in the adsorptive desulfurized gas oil produced in Example 2.

BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, embodiments of the present invention will be specifically described, but the present invention is not limited thereto. The adsorptive desulfurization agent of the present invention contains a carbon material such as activated carbon as a main component and preferably contains, for example, 80% by weight or more, but may contain other components such as a zeolite component described later. The specific surface area can be measured by a so-called nitrogen adsorption method.

[Activated carbon]

 Activated carbon is a carbon material with a well-developed pore structure, and is widely used industrially as an adsorption desulfurization agent and catalyst carrier. Some carbon materials, such as anthracite, exhibit adsorptive activity even in their natural state, but are generally manufactured by carbonizing activated carbon raw material, which is an organic substance (carbonaceous substance), and activating it as necessary. The production method is not limited.

[Activated carbon raw material]

As a raw material for activated carbon, a large amount of carbonaceous materials can be considered, and production conditions vary depending on the type of raw material. As raw materials, plant-based wood, sawdust, coconut shell, pulp waste liquor, fossil fuel-based coal, heavy petroleum oil, or pitch-coke obtained by thermally decomposing them can be used. The starting material for the fibrous activated carbon is a fiber obtained by spinning a synthetic polymer, tar pitch or oil-based pitch. Coal is classified into lignite, bituminous coal and anthracite according to the degree of coalification. Synthetic polymers used as starting materials include phenolic resin, furan resin, polyvinyl chloride resin, polyvinylidene vinylidene resin, waste bra Sticks and the like are mentioned as raw materials. [Carbonization of activated carbon raw material]

 Carbonization is a series of various chemical reactions that enrich carbon, such as the cleavage of bonds caused by heating changes in organic matter and the decomposition, polycondensation, and aromatic cyclization that lead to the conversion to more stable bonds. Is a generic term for The raw material can be heat-treated to obtain coke and char. During this carbonization reaction, water, carbon oxides and light hydrocarbons are volatilized and a liquid is distilled out at the same time. The pore structure that greatly affects the adsorption characteristics of activated carbon changes with the carbonization temperature. Generally, in the production of activated carbon, carbonization is performed in the range of 600 to 800 ° C. to produce a carbon material (carbonized material). However, the conditions are not particularly limited. Absent.

[Activation of charcoal]

 Activation methods after carbonization in the production of activated carbon include gas activation and chemical activation. In Japan, the gas activation method using steam is the mainstream, but the chemical activation method using zinc chloride is still used in the production of powdered activated carbon. In recent years, a new chemical activation method, the alkali E activation method, has also been reported.

[Gas activation method]

 The gas activation method is also referred to as physical activation, and is a method of producing a fine porous activated carbon by contacting a carbon material with steam, carbon dioxide, oxygen, or the like at a high temperature. It is believed that the activation process proceeds in two stages.In the first stage of heating, the unorganized part is selectively decomposed and consumed, and the closed fine pores between the carbon crystals are opened, resulting in a specific ratio. The surface area increases sharply. In the gasification reaction process of the second stage, carbon crystals and the like are consumed by reaction, and mesopores and macropores are formed.

[Chemical activation method]

In the chemical activation method, the raw material is evenly impregnated with the activating chemical, heated and calcined in an inert gas atmosphere, and the fine porous activated carbon is obtained by the dehydration and oxidation reaction of the chemical. It is a method of manufacturing. Activating chemicals include zinc chloride, sulfuric acid, boric acid, nitric acid, hydrochloric acid, phosphoric acid, sodium phosphate, calcium chloride, hydroxide lime, sodium hydroxide, carboxylic acid lime, carbonate lime, Calcium carbonate, sulfuric acid, sodium sulfate, nitrite, chloride, permanganate, sulfur, thiocyanate, and other dehydration, oxidation, and erosion Sex chemicals are used. In chemical activation, the mass ratio of the chemical to be impregnated to the carbonaceous raw material is an important measure of activation.When the mass ratio is small, micropores are generated, and as the mass ratio increases, the pore size increases. To increase the pore volume.

[Sulfuric acid activation method]

 The sulfuric acid used is preferably concentrated sulfuric acid (concentration of about 30 to 40% by weight). The heat treatment after the impregnation is usually performed in a non-oxidizing atmosphere at about 200 to 300 ° C for about 4 to 6 hours.o

[Alkali activation method]

Recently, the K 0 H special chemical activation method and the like, petroleum co one to box the specific surface area 3 0 0 0 m ² Zg or more activated carbon is produced, it is reported that much better adsorption capacity (H. March, D. Crawford: Carbon, 20, 419 (1982), A. N. Wennerberg, TM O'Grady: US Patent 4082694). In Japan, studies have been conducted using various types of carbon materials such as petroleum coke, petroleum pitch, coal pitch, and coconut shells, and studies are being made to enhance the functionality of activated carbon. In particular, it is an effective method for soft carbon such as optically anisotropic pitch-based carbon fiber in which pores cannot be generated by a method such as steam activation. A major feature of this production method is that an alkali (mainly K 0 H) having a mass ratio of about 1 to 5 times that of the carbonaceous material is used. Activate by treating at a predetermined temperature of ~ 900 ° C. After the reaction, the contents are taken out and washed thoroughly with water, whereby the alkali is eluted to obtain activated carbon. The obtained activated carbon has extremely large specific surface areas and pore volumes, and may be able to produce activated carbon with better adsorption performance than other activation methods. Such an activation method is also described in, for example, Japanese Patent Application Laid-Open No. 5-247731. [Adsorption characteristics of activated carbon]

 The adsorption characteristics of activated carbon are essentially determined by the contact between the surface of the activated carbon and the adsorbate molecules and the interaction energy in situ. Therefore, the strength of the interaction is important depending on the relationship between the pore distribution and the size of the adsorbate molecule and the structure of the adsorbate molecule and its physical properties. In addition, liquid-phase adsorption is often a multi-component competitive adsorption, and is complicated by the state of solute molecules in the solvent. The inventor has found that the adsorption capacity of sulfur compounds is not simply proportional to the specific surface area. Fibrous activated carbon having a relatively small specific surface area has a larger adsorption capacity than powdered activated carbon having a large specific surface area. Although various causes are considered, it is considered that the pore structure of the activated carbon has a great influence.

[Fibrous activated carbon]

 Fibrous activated carbon uses carbon fiber as a raw material for activated carbon.When compared with granular activated carbon, it can be processed into various shapes such as a very high adsorption rate, a high adsorption at low concentrations, and a felt shape. There are advantages such as. In the present invention, in order to reduce the outflow of the fibrous activated carbon from the adsorptive desulfurization tank (tower) and to prevent the pressure difference inside the adsorption tank from increasing, the fibrous activated carbon having an average length of 100 m or more is used. Preferred is fibrous activated carbon having an average length of 1 mm or more.

[Carbon fiber]

 In general, carbon fiber refers to PAN (polyacrylonitrile) fiber, pitch fiber melt-spun from strong curryon, petroleum pitch, coal pitch, etc., and is thermally oxidized and crosslinked at 200 to 400 ° C in air. After the reaction, it is a graphitized fiber having a high carbon content obtained by heat treatment in nitrogen at 800 to 1500 ° C and heat treatment at 20000 ° C.

[Pitch]

The pitch includes an isotropic pitch and an anisotropic pitch. Carbon fibers produced from isotropic pitch are inexpensive but have low strength due to poor molecular orientation. In contrast, carbon fibers produced from optically anisotropic (meso-fess) pitch have a high degree of molecular orientation. And exhibit excellent mechanical properties. [Orientation]

 In optically anisotropic pitch-based carbon fiber, it is important to control the orientation of the graphite layer surface inside the fiber. This orientation is substantially controlled in the spinning process such as pitch viscosity during spinning, spinning speed, cooling speed, and nozzle structure. The optically anisotropic pitch-based activated carbon fibers used for adsorbents preferably have a so-called radial orientation in the graphite layer surface in the fibers. [Spinning]

 Examples of the spinning method include melt spinning, centrifugal spinning, vortex spinning, and melt blow spinning, and any of these methods may be used.

[Pitch infusibility]

The pitch is a thermoplastic organic compound, and in order to carry out carbonization while maintaining the fiber form, usually after spinning, infusibilizing treatment is performed to obtain infusible fibers. This infusible reduction is possible to continuously infusibilized in conventional manner by a liquid phase and a gas phase, carried out usually air, oxygen, in an oxidizing atmosphere of N 0 _2, and the like. For example, infusibility in air is performed at an average heating rate of 1 to 15 ° C / min and in a temperature range of about 100 to 350 ° C.

[Light carbonization of infusible fiber]

 The infusibilized fiber can be used as it is in the next activation treatment step. However, since it contains a large amount of low volatile components, it is desirable to perform a light carbonization treatment to obtain a light carbonized fiber. This treatment is performed in an inert gas such as nitrogen, and the treatment temperature range is 400 ° C. or more and 700 ° C. or less.

[Milling of light carbonized fiber]

Infusibilized fibers or lightly carbonized fibers can be activated even in a mat or felt state. Although it can be used as an adsorbent, it can be pulverized (milled) before activation for uniform mixing with chemicals and surface uniformity by activation reaction. If it is excessively fine, uniform activation becomes difficult. As a method of milling, it is effective to use a Victor mill, a jet mill, a cross flow mill, a high-speed rotation mill, or the like. For efficient milling, it is appropriate to cut the fibers by rotating the rotor with blades at high speed, for example.

[Adsorbent shape]

 The adsorptive desulfurizing agent of the present invention can be used in any of fibrous, powdery, particulate and molded products without pulverization, but is repeatedly used by continuously using the adsorptive desulfurizing agent. In the case of regeneration, it is preferable to use it as a molded article of activated carbon. The shape of the molded product can be a granular shape, a honeycomb shape, a mat shape, a felt shape, or the like. When used in a granular form, a spherical shape having a radius of 0.3 to 3 mm is preferable from the viewpoint of the packing density, the adsorption speed and the pressure loss.

[Formation of activated carbon]

When used as a molded article, the powder may be molded and then carbonized and then activated, or the activated powder may be molded, dried and fired. When molding, a binder (binder) can be used as necessary. Examples of the binder include tar pitch, tar-compatible resin, expanded graphite, lignin, molasses, synthetic resin such as sodium alginate, carboxymethyl cellulose (CMC), and phenol resin, and organic resins such as polyvinyl alcohol and starch. Examples include binders, smectites, and inorganic binders such as water glass. These binders may be used to the extent that they can be molded, and are not particularly limited. Usually, about 0.05 to 2% by weight based on the raw material is used. Inorganic substances such as silica, alumina, and zeolite may be mixed to improve the adsorption performance of sulfur compounds that hardly adsorb activated carbon, or the diffusion rate of sulfur compounds by increasing the amount of mesopores and macropores. May be improved. Further, the adsorption performance may be improved by compounding with a metal. [Pretreatment of adsorptive desulfurizing agent]

 The adsorptive desulfurizing agent is preferably dried at about 100 to 200 ° C. in an oxidizing atmosphere such as air in order to remove a small amount of water adsorbed on the adsorptive desulfurizing agent as a pretreatment. If the temperature exceeds 200 ° C, it reacts with oxygen and the weight of the adsorptive desulfurizing agent decreases, which is not preferable. On the other hand, in a non-oxidizing atmosphere such as nitrogen, it is preferable to dry the adsorptive desulfurizing agent at about 100 to 80 (TC. Particularly, when the adsorbing desulfurizing agent is heated at 400 to 800 ° C in a non-oxidizing atmosphere, Organic substances and oxygen content are removed, and the adsorption performance is improved.

[Desorption regeneration of adsorbent]

 The adsorptive desulfurizing agent after the adsorptive desulfurization can be easily desorbed and regenerated by washing with a solvent such as toluene, alcohol, and acetone, heating under a nitrogen atmosphere and heating under reduced pressure, and can be used repeatedly. . In particular, by heating under a non-oxidizing atmosphere (usually under a nitrogen atmosphere) and under Z or reduced pressure, sufficient regeneration is possible in a short time. It is also possible to use water or steam as a source.

[Specific surface area of carbon material]

Further, in the adsorptive desulfurization agent of the present invention, the micropore specific surface area S micro [m ² / g], the micropore external pore volume V ext [cm ³ / g], It is preferable that the pore external specific surface area S ext [m ² / g] satisfies the following expression (1).

Smicrox2xVext / Sext> 3.0-(1) The carbon material used in the adsorptive desulfurizing agent of the present invention preferably has a large specific surface area and a mesopore having a pore diameter of about 20 to 50 OA. And The measurement of parameters such as specific surface area, pore diameter and pore volume used in the analysis of carbon materials is generally performed by gas adsorption using physical adsorption based on the intermolecular force acting between gas molecules and the solid surface. The nitrogen adsorption method is used. Many carbon materials have an average pore diameter of 2 OA or less. Care must be taken in the analysis. The BET (Brunoue "-E 麵 ett-Teller") method, which is generally used, is a method of calculating the specific surface area of a carbon material based on the following equation (2).

 x / V / (1 -x) = 1 / Vm / C + (C— 1) x / Vm / C · ■ ■ (2) where x is relative pressure and V is adsorption when relative pressure is X Quantity, Vm is the monolayer adsorption quantity, and C is a constant (> 0). That is, in the BET method, the constant C needs to be a positive value, and when the value is negative, it is not appropriate. When the constant C <0, parameters such as the specific surface area, pore diameter, and pore volume are often obtained by the Langmuir method. In the Langmuir method, the specific surface area of the carbon material is determined based on the following equation (3).

x / V = x / Vm + 1 / Vm / C _L ■ ■ · (3)

Here, X is the relative pressure, V is the amount of adsorption when the relative pressure is X, Vm is the amount of monolayer adsorbed, and C _L is a constant (> 0). Therefore, even if the constant C is negative in the Langmuir method, it is not appropriate. Micropores can be quantified by the t-plot method. In the t-plot method, the change in the amount of carbon material adsorbed with respect to the thickness t of the adsorption layer is plotted by plotting the thickness t of the adsorption layer (a function of relative pressure) on the horizontal axis and the amount of adsorption on the vertical axis. In plot Bok properties, the slope of the t plot Bok exists thickness region t _B continuously decreases adsorption layer. In this region t _B , the micropores are filled with the adsorbed gas (nitrogen) with the progress of multi-layer adsorption, and do not contribute as a surface. This phenomenon, since due to the filling of the micropores is happening in the thickness region t _B of the adsorption layer, in a small area and a large area than the thickness t of the region t _B of the adsorption layer, the microphone of the gas molecules Since there is no filling in the mouth pores and no capillary condensation, the slope of the t plot is constant. Therefore, the thickness t is larger than the area t _B region of the adsorption layer, i.e. draw a straight line in the region where the filling of the micropores of the gas molecules is completed, the contribution from the slope as the surface other than the micropores of the carbon material The specific surface area (external specific surface area) of the part to be determined is determined. Further, when converted to the value of the intercept of the vertical axis of the line thickness t of the adsorption layer is pulled at a greater area than t _B to the liquid, micropore volume is obtained. In summary, the adsorption amount of carbon material V, My Kuropoa external specific surface area ^{S ex t [m 2 / g} ], micropore specific surface area ^{S mi cro [m 2 / g} ], micropore volume Vm icro [cm ³ / g] and micropore external pore [0306336] The volume Vex t [cmVg] is obtained by the following equations (4) to (8).

V = at + 5 (t> t _B ) ■ · ■ (4)

S ex t = x1 0 ³ XD--■ (5)

 Vm i c ro =; Sx D... (6)

 Smi cro = Sa-S ex t ■ (7)

 Vex t = Va— Vmi cr o · · · (8)

Here, a [cm ³ (STP) / g / nm] is the slope of the straight line of the t plot in a region where the thickness t of the adsorption layer is larger than the region t _B , and 3 [cm ³ (STP) / g / nm]. ] (0.001 547 when the nitrogen used as a gas) intercept of the straight line and the longitudinal axis of the t plot Bok in the region greater than the thickness t of the region t _B of the adsorption layer, D is the density conversion coefficients are [cm ³ 1 q / cm ³ (ST P)], Sa is the total specific surface area [m ² / g], and Va is the total pore volume [cm ³ / g]. Here, Sa is the total specific surface area obtained by the above-mentioned BET method, Langmuir method, or the like. Va can be defined as a value obtained by converting the amount of adsorbed gas at a pressure close to the saturated vapor pressure into a liquid.For example, the adsorbed amount at a relative pressure of 0.95 [cm ³ (STP) / g ] Multiplied by D. Most of the carbon materials have micropores, and there are few mesopores outside the micropores. However, the inventors' verification experiments have found that a small amount of mesopores existing outside the micropore has a great effect on sulfur compound adsorption. The present inventor has found that a value of 2XVeXt / SExt is suitable as an index indicating the influence of mesopores. Since the value 2 xVa / S a represents the average pore radius (Da / 2) or the distance between the walls of the plate-like pores when the pores are assumed to be cylindrical, 2 xVe X tZS ex t Is an index that represents a value close to the average pore radius (Dext / 2) of the mesopore or the distance between the walls. Further, in the present invention, regarding the adsorption of the sulfur compound, it is preferable that the specific pore surface area and the average pore radius of the mesopores (or the distance between the walls) of the carbon material are larger. In particular, the product of both (Smicrox 2xVext / Sext) It has been found that the larger the value of) is, the more the carbon material adsorption performance is improved. Specifically, when the value of S Micro X 2 XV e X t / S e X t is 3.0 cm ³ / g or more, more preferably 5.0 cm ³ / g or more, the adsorption performance of the carbon material is improved. I understood that. Although the cause is not clear, the adsorption performance of the carbon material does not simply depend on the amount of mesopores. This is considered to indicate that a mesopore with a diameter is required.

[Carbon material packing density]

 In the adsorptive desulfurizing agent of the present invention, it is desirable to sufficiently increase the packing density of the carbon material used in the adsorptive desulfurizing agent in order to reduce the sulfur content in light oil to 15 ppm or less. Packing density of carbon material C [g-ad sorbent / m 1-adsorbent] and adsorption capacity per unit weight of carbon material when the sulfur concentration of light oil in the liquid phase is 15 ppm A [gS / g- ad sorbent] and the density B [g / ml] of gas oil must satisfy at least the following formula (9).

 OB X k ÷ A ■ ■ · (9)

Here, k = 0.00001 5 [gS / g]. When the sulfur concentration of light oil in the liquid phase is 15 ppm, the adsorption capacity A per unit weight of the carbon material can be obtained from the adsorption isotherm at the temperature of the adsorption desulfurization step. The above-mentioned carbon materials have excellent adsorption performance for thithiophenes, benzothiophenes, and dibenzothiphenes, and have a higher adsorption performance for benzothiophenes, dibenzothifenphens, and especially dibenzothifenphens than zeolite components. And the effect of aromatics is small. On the other hand, the zeolite component has excellent adsorption performance for mercaptans, chain sulfides, 璟 -sulfides, and thiaphenes, and is superior to carbon materials in mercaptans, chain sulfides, and the like. Excellent adsorption performance for cyclic sulfides. Therefore, depending on the type and amount of the organic sulfur compound contained in the petroleum fraction, the organic sulfur contained in the petroleum fraction can be obtained by using the carbon material as the adsorptive desulfurizing agent in combination with the zeolite component. Compounds can be efficiently removed. Examples of the type of zero-age light include an X-type light, a Y-type light, an L-type light, a mordenite, a ferrite light, and a 5-type light. 6336

Ze Sai Lai I, general _{formula: xM 2 / n O 'A} 1 2 0 3' y S i 0 2 'z H 2 〇 (where, n represents the valence of the cation M, X is the number of 1 or less , Y is a number of 2 or more, and z is a number of 0 or more), which is a general term for crystalline hydrous aluminosilicate. Structure of zero Sai Lai I, S i or a structure in which <array tetrahedral structure S i 0 ₄ or A 1 0 ₄ are three-dimensionally regularity centered on A 1, for example, I NTER nat io na l Z eo l te As soci at ion (I ZAj Structure Commi sion page http: // www. iza— structure, org / . since tetrahedral structure of a 1 0 ₄ are negatively charged, it holds a charge compensating cation ion such as alkali metal and Al power Li-earth metal in the pores and cavities. charge compensation cation , it is possible to easily exchange with another cation such as proton. also, by acid treatment or the _{like, S i 0 2 / Α Ί} 2 0 3 molar ratio is increased, the solid acid amount acid strength is increased Since the acid strength has little effect on the adsorption of sulfur compounds, it is preferable not to lower the amount of solid acid. Lai I, general formula:. XNa ₂ 0 ■ represented by _{A 1 2 0 3 · y S} i 0 2, X rather 1 and,, y <1 0 is preferably used et S i 0 ₂ / A 1 ₂ The molar ratio of O ₃ is preferably 1 Omo 1 / moΊ or less, and is preferably used.The mordenite which is preferably used in the present invention and is used is represented by the general formula: xNa ₂ 0 ■ A 1 ₂ 0 ₃ ■ y S is represented by i 0 _2, X rather 1, _{and,. S i 0 2 / a} 1 2 0 3 molar ratio represented by y rather 20 to 2 Omo 1 / mo Ί less is preferably used. the present invention The properties of the zeolite used are as follows: the crystallinity is 80% or more, especially 90% or more, the crystallite size is 1 mm or less, and the average particle size is 30 m or less. especially less 1 O zm, specific surface area 300 meters ² / g or more, it is preferable to Japanese is 400 meters ² / g or more.

NaX-type zeite, NaY-type zeite, and Na-mordenite are X-type zeite, Y-type zeite, and mordenite in which the charge-compensating cation is sodium. The L-type zeisai-lite and the K-huerieri-light are L-type zeisai-lites and hu-erie-lites in which the charge-compensating cation is potassium. When the charge-compensating cation is hydrogen, thiocyanates and benzothiaphenes react with sulfur compounds or aromatics such as toluene even at room temperature to form oligomeric heavy substances, and the adsorbent surface is damaged. Coating is not preferred because it inhibits the adsorption of sulfur compounds. Charge compensation cation, lithium, alkali metals such as sodium, potassium, rubidium, cerium, magnesium, force Rushiu厶, strontium, Bruno ¹ (alkaline earth metals such as Liu厶metal, manganese, iron, co Bal Bok, nickel And transition elements such as copper, zinc, ruthenium, lead, silver, and lanthanum, etc. In particular, a zeolitic light having an alkali metal ion as a charge cation is preferably used. The above-mentioned zailite light can be used as it is, but a molded article containing these zailite lights in an amount of 30% by weight or more, particularly 60% by weight or more is preferably used. As long as the differential pressure does not increase, a small shape, especially a spherical shape, is preferable, and the spherical shape has a diameter of 0.5 to 5 mm. Is preferably 1 to 3 mm.In the case of a columnar shape, the diameter is 0.1 to 4 mm 0, particularly 0.1 to 2 mm 0, and the length is 0.5 to 5 times the diameter. In the case of using a genuine light as a molded product, a semi-finished product is molded, dried and dried as described in JP-A-4-198011. The binder may be baked, or may be mixed with a binder (binder) as necessary, and then dried and baked. Examples of the _c binder include alumina and smectite. Examples of such binders include inorganic binders such as clay and water glass, etc. These binders may be used to the extent that they can be molded, and are not particularly limited. About 0.5 to 30% by weight of inorganic fine particles such as silica, alumina and other zeolite and the activity used in the present invention. By mixing organic materials, such as the, or improved adsorption performance of peptidase old Lai I sulfurized compound hardly adsorbed to or increase the abundance of mesopores and macropores sulfur The diffusion rate of the compound may be improved. Further, the adsorption performance may be improved by compounding with a metal. In the case of particles, it is preferable that the breaking strength of the carrier is 3.0 kg / pellet or more, especially 3.5 kgZ pellet or more, since cracking of the absorbent does not occur. When the above-mentioned zeolite component is used together with the carbon material as the adsorptive desulfurizing agent of the present invention, the adsorptive desulfurizing agent containing the carbon material and the adsorptive desulfurizing agent containing the zeolite component are separately disposed. For example, the petroleum fraction can be arranged in series with the flow of the petroleum fraction, and the petroleum fraction can be sequentially contacted with the carbon material, the hydrocarbon, and the zeolite component. Alternatively, an adsorptive desulfurizing agent containing a carbon material and an adsorptive desulfurizing agent containing a zeolite component may be physically mixed and used as a mixed adsorptive desulfurizing agent. Still further, adsorption desulfurization agent particles produced so that the carbon material and the zeolite component are simultaneously contained in the adsorption desulfurization agent particles may be used. The amount or content of the zeolite component depends on the type of the sulfur compound contained in the gasoline fraction, but is preferably 0 to 6 Owt% based on the total amount of the carbon material and the zeolite component.

[Petroleum fraction to be desulfurized]

 The petroleum fraction is a liquid mainly composed of hydrocarbons obtained by refining crude oil.The boiling point of the hydrocarbons mainly contained is 30 to 400 ° C. Preferably, the sulfur content of the petroleum fraction is 500 ppm or less, particularly 200 ppm or less, and more preferably 50 ppm or less. Further, a petroleum fraction having a low content of a nitrogen compound that inhibits adsorption of a sulfur compound, for example, a petroleum fraction of 10 ppm or less is more preferable. Examples of such a petroleum fraction include a gas oil fraction, a kerosene fraction, and a gasoline fraction. These fractions are used as raw materials for petroleum products such as gas oil, kerosene, gasoline and hydrocarbon fuel for fuel cells.

[Light oil fraction]

The gas oil fraction mainly consists of hydrocarbons having about 16 to 20 carbon atoms. Density (1 5 ° C) is, 0. 790~0. 880 g / cm 3 or so, boiling range 1 00 ° C~400 ° C approximately, 1 0% distillation temperature is 1 60 ° C~280 ° C The 90% distillation temperature is around 280 ° C ~ 360. C or less, and mostly paraffinic hydrocarbons. In the present invention, 90% fraction of gas oil fraction The outlet temperature is preferably 310 ° C. or higher, particularly 320 ° C. to 360 ° C., and more preferably 340 ° C. to 360 ° C.

[Kerosene fraction]

The kerosene fraction is mainly composed of hydrocarbons having about 12 to 16 carbon atoms. Density (1 5 ° C) is 0. 770~0. 850 gZcm ³ mm, boiling range 1 30 ° C~320 ° C approximately, 1 0% distillation temperature is 1 50 ° C~ "! 90 ° C approximately The 95% distillation temperature is about 200 ° C to 300 ° C or less, and there are many paraffinic hydrocarbons.

[Gasoline fraction]

The gasoline fraction mainly consists of hydrocarbons with about 4 to 11 carbon atoms. Density (15 ° C) is 0.71 0 to 0.783 g Z cm ³ or less, boiling range is about 20 ° C to 220 ° C, and 10% distillation temperature is about 35 ° C to 70 ° C or less, 50% distilling temperature is 75 ° C or more to 110 ° C or less, and 90% distilling temperature is about 110 ° C to 180 ° C or less. For use in automobiles and other gasoline engines, fractions with high octane numbers are obtained by catalytic cracking, catalytic reforming, and alkylation. Generally, aromatics and low-boiling isoparaffins and orefins have a high octane number. In the method for producing light oil according to the present invention, first, the specific surface area is preferably 500 m ² / g or more.

2000m ² / g or more, more preferably <adsorbs an adsorbent desulfurization agent containing a carbon material that satisfies the above formula (1) and a gas oil fraction in a liquid phase containing a sulfur compound of 500 ppm or less Contact in desulfurization tower. At this time, it is preferable to control the temperature in the adsorption desulfurization tower to 80 ° C or less. After the adsorptive desulfurization step, the adsorptive desulfurizer is washed with an aromatic solvent, preferably heated to 50 ° C or more, more preferably 80 ° C or more, preferably toluene, to remove the sulfur compound from the desulfurizer. To regenerate the adsorptive desulfurization agent. Sulfur compounds and aromatic solvents contained in the effluent flowing out of the adsorption desulfurization tower in this desorption regeneration step are separated from each other by distillation separation, membrane separation, solvent extraction, adsorption separation, etc., preferably by distillation separation. Is done. The separated sulfur compound can be mixed into heavy oil or the like, or consumed in a boiler equipped with an exhaust gas treatment device. Also separate The aromatic solvent thus obtained can be reused in the desorption regeneration step. In the gas oil production method of the present invention, for example, the adsorption desulfurization step and the desorption regeneration step are preferably alternately repeated using a plurality of adsorption desulfurization towers. This makes it possible to produce gas oil having a sufficiently low sulfur concentration over a long period of time with high efficiency and relatively low equipment costs and operation costs. In the gas oil production method of the present invention, it is preferable to add a step of recovering the insufficiently desulfurized light oil remaining in the adsorptive desulfurization tower after the adsorption desulfurization step and returning it to the raw gas oil. By this step, loss of light oil can be reduced. The following method is preferred as a method for collecting light oil. First, the inside of the adsorption desulfurization tower is washed with a paraffinic solvent that does not desorb a sulfur compound from the adsorption desulfurization agent, preferably hexane or decane. Next, the paraffinic solvent and the gas oil fraction contained in the effluent flowing out of the adsorption desulfurization tower are separated from each other by a separation operation such as distillation separation, membrane separation, solvent extraction, adsorption separation, or the like, preferably by distillation separation. Then, the separated gas oil fraction is returned to the raw gas oil, and the separated paraffinic solvent is reused in the washing step in the adsorptive desulfurization tower. As another method of recovering light oil, a gas such as nitrogen, helium, argon, hydrogen, oxygen, or water vapor, preferably an inert gas such as nitrogen, is supplied into the adsorption desulfurization column at ordinary temperature or under heating, and the pressure is adjusted. For example, a method of extruding light oil may be used. Further, in the gas oil production method of the present invention, the aromatic type agent used for washing is prevented from being mixed into the product gas oil fraction, the loss of the product gas oil is reduced, and immediately after the start of the distribution of the material gas oil fraction. In order to obtain sufficient adsorptive desulfurization performance, it is preferable to include a step of removing an aromatic solvent from the inside of the adsorptive desulfurization tower after the desorption regeneration step. To remove the aromatic solvent, a paraffinic solvent, preferably hexane or decane, may be passed through the adsorption desulfurization tower. In this case, the mixed solution of the aromatic solvent and the paraffin solvent flowing out of the adsorptive desulfurization column is subjected to separation operations such as distillation separation, membrane separation, solvent extraction, adsorption separation, and the like. It can be separated into paraffinic solvents and reused. Further, as another method for removing the aromatic solvent, a method in which the solvent is removed at room temperature or under heating Gas, such as nitrogen, helium, argon, hydrogen, oxygen, and water vapor, preferably, an inert gas such as nitrogen, is supplied into the adsorptive desulfurization column, and an aromatic solvent is extruded at the pressure. Is also good. After the aromatic solvent is removed with the paraffin solvent to regenerate the adsorptive desulfurizing agent, the gas oil fraction (raw gas oil) containing sulfur compounds is passed through the adsorptive desulfurization tower. , Paraffin solvent is mixed in the initial distillate of gas oil from the adsorption desulfurization tower. In this case, the gas oil initial effluent mixed with the paraffinic solvent can be separated into a paraffinic solvent and a gas oil fraction by a separation operation such as distillation separation, membrane separation, solvent extraction, and adsorption separation, preferably by distillation separation. . The separated gas oil fraction can be mixed into the product gas oil or the raw gas oil, and the separated paraffinic solvent can be reused. By adding such a step, higher quality light oil can be obtained. The adsorptive desulfurization tower used in the gas oil production method of the present invention may be in any form such as a fixed bed or a simulated moving bed, but a gas oil fraction having a sulfur content of about 15 ppm from a feed gas oil having a sulfur content of several + Ppm. For the production of waste, it is economical to install two fixed bed adsorption desulfurization towers and use them alternately. In this method, it is preferable that the flow direction of the feed gas oil and the aromatic solvent is opposite (countercurrent), but the control may be complicated, so that the flow may be the same (cocurrent). When the feed gas oil flows through the adsorptive desulfurization tower, the pressure difference inside the adsorptive desulfurization tower increases depending on the packing density of the adsorptive desulfurizing agent and the operating temperature. Therefore, the feed direction of feed gas oil is preferably vertically downward. Hereinafter, the desulfurization process of the gas oil fraction in the case of one adsorption desulfurization tower will be specifically described with reference to FIG. Feed gas oil is supplied from line 11 to adsorption desulfurization tower 1, and the adsorptive desulfurization of feed gas oil is performed in adsorption desulfurization tower 1 (adsorption desulfurization step). The adsorptive desulfurized gas oil is discharged as product gas oil from the adsorptive desulfurization tower 1 via the path 12. Detected that sulfur concentration in light oil discharged from adsorption desulfurization tower 1 exceeded a predetermined concentration Then, the supply of the feedstock light oil from the passage 11 is stopped, and the paraffin-based solvent flows from the passage 13 to the adsorptive desulfurization tower 1. The paraffin-based solvent flushes away the light oil stored in the adsorption desulfurization tower 1 (light oil recovery process). The path 12 is closed immediately before the paraffin solvent passed through the adsorption desulfurization tower 1 is discharged from the adsorption desulfurization tower 1. The mixture of light oil and paraffinic solvent that has flowed out of the adsorption desulfurization tower 1 is sent to the distillation tower 3 from the path 14 via the tank 5. The mixture of light oil and paraffinic solvent is distilled and separated in the distillation column 3, and the separated light oil is added to the feed gas oil in path 11 via path 15 and the separated paraffin solvent is separated from path 16 It is circulated to the tank 8 and reused in the light oil recovery process and the desorbent removal process described later. In the light oil recovery step, when the amount of light oil flowing out of the outlet of the adsorptive desulfurization tower 1 falls below a predetermined value, the flow of the paraffin-based solvent from the path 13 to the inlet of the adsorptive desulfurization tower 1 is stopped. Next, the aromatic solvent heated by the exchange heater 9 from the path 17 is circulated to the adsorptive desulfurization tower 1. The aromatic solvent supplied to the adsorptive desulfurization tower 1 pushes down the paraffinic solvent accumulated in the adsorptive desulfurization tower 1 and the sulfur compounds adsorbed by the adsorptive desulfurization agent to desorb and regenerate the adsorptive desulfurization agent ( Desorption regeneration process). The path 14 is closed immediately before the aromatic solvent supplied to the adsorptive desulfurization tower 1 flows out of the adsorptive desulfurization tower 1. The mixed solution of the aromatic solvent, the paraffinic solvent and the sulfur compound that has flowed out of the adsorption desulfurization tower 1 is sent to the distillation tower 4 from the passage 18 via the tank 6. In the distillation tower 4, a mixture of an aromatic solvent, a paraffin solvent and a sulfur compound is separated by distillation. The separated aromatic solvent is circulated to the tank 7 via the path 19 and reused, and the separated paraffin solvent is used for reuse in the light oil recovery step and the desorbent removal step described later. Sent to evening 8 via route 20. On the other hand, the separated sulfur compounds are discharged from route 21 and mixed with heavy oil or the like, or consumed in a boiler equipped with an exhaust gas treatment device. When a mixture of a sulfur compound and an aromatic solvent is separated by distillation, the boiling point difference and the volume ratio of the two are large. Therefore, the sulfur compound must be recycled to the mixture, or a slight light oil fraction must be recycled. By mixing with, the state of distillation separation can be stabilized. 6336 After the desorption and regeneration of the adsorptive desulfurizing agent in the adsorptive desulfurization tower 1 is sufficiently performed, the path 17 is closed and the paraffin-based solvent is flown into the adsorptive desulfurization tower 1 again from the path 13. The paraffin solvent supplied to the adsorptive desulfurization tower 1 flushes the aromatic solvent stored in the adsorptive desulfurization tower 1 to wash the adsorptive desulfurization tower 1 (desorbent removal step). The mixed solution of the aromatic solvent and the paraffin solvent flowing out of the adsorption desulfurization tower 1 is sent from the path 18 to the distillation tower 4 via the tank 6. In the distillation column 4, the mixture of the aromatic solvent and the paraffin is separated by distillation. The separated aromatic solvent is sent to tank 7 via line 19 for reuse. Further, the separated paraffin solvent is also circulated to the tank 8 via the path 20 and reused. After the adsorptive desulfurization tower 1 is sufficiently washed, the path 13 is closed, and the feed gas oil is again supplied to the adsorptive desulfurization tower 1 from the path 11. The gas oil supplied to the adsorption desulfurization tower 1 flushes the paraffinic solvent stored in the adsorption desulfurization tower 1. Immediately before the gas oil supplied to the adsorption desulfurization tower 1 flows out of the adsorption desulfurization tower 1, the path 18 is closed and the path 14 is opened. The mixture of the gas oil and the paraffin-based solvent flowing out of the adsorption desulfurization tower 1 is sent to the distillation tower 3 through the open path 14 and the tank 5. The mixed gas of gas oil and paraffin is distilled and separated in the distillation tower 3, and the separated gas oil is circulated to the feed gas oil via route 15 and the separated paraffin solvent is recycled for later reuse in route 16. ^> O After the paraffinic solvent is sufficiently discharged from the adsorption desulfurization tower 1, the path 14 is closed and the product gas oil is discharged from the opened path 12 (adsorption Desulfurization step). By repeating the above process using the system shown in Fig. 1, gas oil with a sufficiently low sulfur concentration can be produced over a long period of time at relatively low equipment costs and operating costs. By the way, in order to obtain a gas oil fraction with a sulfur content of about 10 ppm from a raw gas oil with a sulfur content of about 50 ppm, or from a sulfur-free gas oil with a sulfur content of 10 ppm or less, zero sulfur with a sulfur content of 1 ppm or less. To produce light oil, an intermediate tank at the outlet It is preferable to use a manufacturing apparatus in which a plurality of adsorption desulfurization towers having In production equipment using multiple adsorption desulfurization towers, if the sulfur concentration of product gas oil at the outlet of the most downstream adsorption desulfurization tower exceeds the specified concentration among the several adsorption desulfurization towers used for adsorption desulfurization Then, the most downstream adsorption desulfurization tower is prepared separately from some of the adsorption desulfurization towers used for the adsorption desulfurization, and is connected in series to the adsorption desulfurization tower immediately after the adsorption desulfurization agent is regenerated. On the other hand, the most upstream adsorption desulfurization tower of some adsorption desulfurization towers used for adsorption desulfurization is subjected to a desorption regeneration step to regenerate the adsorption desulfurization agent. The use of such a cyclic production system using a plurality of adsorptive desulfurization towers makes it possible to produce gas oil with a low sulfur concentration for a longer period of time, and is economical. 2 and 3 show an example of the light oil production apparatus of FIG. Figures 2 and 3 show the use of an adsorption desulfurization tower of 3 ± r.p.m., one tower for replacement of gas oil with hexane, one tower for desorption with toluene, and one tower for replacement of toluene with hexane. FIG. 1 shows a schematic diagram of a six-column cyclic light oil production apparatus. As shown in (Step 1) in Fig. 2, these towers are composed of three adsorption desulfurization towers from the left of the drawing, a toluene replacement tower with hexane, a desorption tower with toluene, and a light oil replacement tower with hexane. It works in order. When the sulfur concentration of the product gas oil at the outlet of the most downstream adsorption desulfurization tower (third tower from the left) exceeds a predetermined concentration, as shown in (Step 2) in FIG. The third column (from the left) will be connected to the column immediately after the adsorbent desulfurization agent on the right has been regenerated, ie, the column for the replacement of toluene with hexane (the fourth column from the left). In other words, at the stage of (Step 2), the toluene replacement tower with hexane (fourth tank from the left) is changed to the most downstream adsorption desulfurization tower. On the other hand, the most upstream adsorption desulfurization tower (first tower from the left) is switched to a gas oil replacement tower with hexane, as shown in (Step 2) in Fig. 2, and the light oil accumulated in the tower is It is flushed and displaced by hexane. As described above, of the three columns used as adsorption desulfurization towers, whenever the sulfur concentration of the product gas oil flowing out of the most downstream adsorption desulfurization tower exceeds a predetermined concentration, the most downstream adsorption desulfurization tower is on the right. Will be connected to the tower immediately after regeneration, and the most upstream adsorption desulfurization tower will be washed with hexane. In other words, in the six-tower cyclic light oil production system shown in FIGS. 2 and 3, as shown in (Step 1) to (Step 6) in FIG. 2 and FIG. Every time the sulfur concentration of the product gas oil discharged from the desulfurization tower exceeds the specified concentration, the processes performed in those towers (adsorption, adsorption, hexane substitution, desorption hexane substitution) are shifted from left to right in the drawing. Shift. Further, in the gas oil production method of the present invention, as a pretreatment of the adsorptive desulfurizing agent, the adsorptive desulfurizing agent may be used at 100 to 200 ° C. in an oxidizing atmosphere such as air to remove a small amount of adsorbed moisture. Drying at about C is preferred. However, if the temperature exceeds 200 ° C., it reacts with oxygen and the weight of the adsorbed desulfurizing agent is reduced, which is not preferable. When heat treatment is performed in a non-oxidizing atmosphere such as nitrogen as a pretreatment of the adsorptive desulfurizing agent, it is preferable to dry the adsorptive desulfurizing agent at about 100 to 800 ° C. Heat treatment at 400 to 800 ° C. is particularly preferable because organic substances and oxygen contained therein are removed and the adsorption performance is improved. The fibrous activated carbon used as the carbon material of the adsorptive desulfurizing agent in the method for producing gas oil of the present invention is 4-methyldibenzotifenphen (4-MDBT), which is a hardly desulfurized compound among the sulfur compounds contained in gas oil. Benzothiophenes such as 4,6-dimethyldibenzothienephen (4,6-DMDBT) can be selectively adsorbed. Therefore, the composition distribution of the sulfur compounds remaining in the gas oil desulfurized by the gas oil production method of the present invention is different from the composition distribution of the sulfur compounds remaining in the gas oil desulfurized by the conventional hydrorefining process. . In particular, it should be noted that the residual ratio of 4,6-DMDBT, which is difficult to desulfurize in the hydrorefining process, is significantly reduced by the desulfurization method of the present invention. That is, the light oil obtained by the present invention has a sulfur concentration of 15 ppm or less. Moreover, the 90% distillation temperature hardly changed before and after desulfurization, indicating that the desulfurization method of the present invention did not adversely affect the quality of light oil. Further, by combining the desulfurization method of the present invention with the conventional hydrorefining, it is possible to further reduce the sulfur content more efficiently. Most of the sulfur compounds remaining in gas oil desulfurized by hydrorefining are alkyldibenzothienephenes, which are difficult to desulfurize. Therefore, when gas oil desulfurized to a sulfur concentration of 10 ppm or less by hydrorefining is further desulfurized by the desulfurization method of the present invention, alkyldibenzothiene fuenes are selectively adsorbed and removed. Gas oil with a sulfur concentration of 1 ppm or less can be obtained efficiently. Further, if hydrorefining is performed as a pre-step of the desulfurization method of the present invention, the nitrogen compound is removed from the gas oil fraction, and the desulfurization effect of the adsorptive desulfurization agent is further improved. Activated carbon, particularly fibrous activated carbon, used in the adsorptive desulfurizing agent of the present invention has a property of selectively adsorbing polycyclic aromatics, particularly aromatics having two or more rings. Therefore, the proportion of polycyclic aromatics remaining in the gas oil refined by the desulfurization method of the present invention is lower than the proportion of polycyclic aromatics remaining in the gas oil refined by desulfurization by conventional hydrorefining, that is, The light oil obtained by the present invention has a sulfur concentration of 15 p.pm or less and achieves a ratio of two or more rings of aromatics to total aromatics of 7% or less. The ratio of tricyclic aromatics to total aromatics is less than 0.5%. Therefore, it is understood that environmentally desirable light oil can be obtained by using the desulfurization method of the present invention. If the adsorptive desulfurized gas oil obtained by the production method of the present invention is mixed with a synthetic gas oil such as GTL (Gas To Liquid), a gas oil having an extremely low sulfur content and an extremely low polycyclic aromatic content can be efficiently used. Can be manufactured. If the sulfur content is reduced to 1 ppm or less, it is possible to reduce the sulfur poisoning of the noble metal catalyst for hydrogenating the benzene ring, the so-called nuclear hydrogenation catalyst. By reducing the sulfur content to 1 ppm or less by adsorption desulfurization and then hydrogenating it with a noble metal-based nuclear hydrogenation catalyst, light oil containing neither sulfur nor aromatic components can be produced efficiently. Example 1

In Example 1, (hereinafter, referred to as the adsorbent) adsorptive desulfurization agent as, activated carbon fiber A having a specific surface area of about 20 00m ² / g, the activated carbon fiber B及beauty specific surface area of the specific surface area about 1 000 m ² / g 1 500 m ² / g powdered activated carbon (D arco KB) manufactured by A1drich Co., Ltd. was prepared, and the adsorption characteristics of each adsorbent were measured.

[Pretreatment of adsorbent]

As a pretreatment for each adsorbent prepared in this example, each adsorbent was dried at 150 ° C for 3 hours. Was. Further, for comparison with the three adsorbents above, Tosoh one company Ltd. N a as adsorbents Y-type peptidase old Lai Bok powder _{HSZ- 320 NAA (S i 0 2} / A 1 2 0 3 ratio: 5 . 5mo l / mo l, N a 2 0 / A 1 2 0 3 ratio:. 1 01 mo 1 / mo 1, specific surface area: 700m ² / g, crystallite size:.. ◦ 2~0 4 (^ , particles Kai: 7 0 171), Tosoh - company Ltd. ^ 1丫型peptidase old Rai Bok powder _{HSZ- 32 OHOA (S i 0 2} / A 1 2 0 3 ratio: 5. 7 mo 1 / mo 1 s Na ₂ 0: 3.8 wt./., Specific surface area: 550 m ² / g, Crystallite diameter: 0.2-0.4 m, Particle diameter: 6-10 Atm) Rye Bokukohitsuji HSZ-331 HSA (S i 0 2 / A 1 2 0 3 ratio: 6. 2mo l / mo l, Na 2 0: 0. 20 wt%, specific surface area: 650 m ² / g, a crystallite diameter:. 0. 7~1 0 m, the particle size: 2 to 4 m), Tosoh one company manufactured HUSY type peptidase old Lai Bok powder _{HSZ- 330 HUA (S i 0 2} / A 1 2 0 3 ratio: 6 . Omo 1 / mo 1, N a 2 0: 0. 2 1 wt%, specific surface area: 550m ² / g, crystallite size:. 0. 2~0 4; m, particle size: 6-8 zm), KL made by Tohso One Company Ze old Lai Bok powder HSZ- 500 K0A (S i (^ ΖΑ Ί 2 0 3 ratio: 6. 1 mo 1 / mo K Na 2 0: 0. 21 wt%, K 2 0: 1 6. 8wt%, the ratio . surface area: 280m ² / g, crystallite size: 0 · 2~0 4 m, the particle diameter: 2~4; um), Tosoh one company manufactured H Morudenai preparative powder _{HSZ- 64 OHOA (S i 0 2} / A 1 ₂ 0 ₃ ratio: 1 8. 3 mo 1 / mo 1, Na 2 0: 0. 04wt%, specific surface area: 380 m ² / g, crystallite size:. 0. 1 x0 5Atm, particle diameter: 1 0 ~1 2μΓη), Tosoh - company Ltd. N a Morudenai Bokukohitsuji _{HSZ- 642 AA (S i 0 2} / A 1 2 0 3 ratio: 1 8. 3mo l / mo l , Na 2 0 / A 1 2 0 ₃ ratio: 1.04 mol / mol, specific surface area: 360 m ² / g, crystallite diameter: 0.1 x 0.5 m, particle diameter: 10 to 12 yum), K-Felierie manufactured by Tohso Corporation Bok powder _{HSZ- 72 OKOA (S i 0 2} / A 1 2 0 3 ratio: 1 8. 2mo 1 / mo 1 , Na 2 0:. 1 3 wt% s K 2 0: 5. 5 wt%, specific surface area : 1 70m ² / g, crystallite size: 1 m or less, particle size:. 20 to 30 m) and manufactured by Wako Pure Chemical Industries, Ltd. N a X-type peptidase old Lai Bok powder F- 9 (S i 0 ₂ / A 1 ₂ 0 ₃ ratio: 2. 5 mo l / mo l , a specific surface area: 59 1 m ² / g) were prepared, respectively. These adsorbents were also dried at 400 ° C. for 3 hours as a pretreatment. Furthermore, silica gel WAK0GEL-G (specific surface area: 687 m ² / g) manufactured by Wako Pure Chemical Industries, activated alumina F-200 (specific surface area: 350 m ² / g) manufactured by Alcoa, and oxidation manufactured by Orient Catalyst Co., Ltd. Copper-supported alumina NK—3 1 1 (copper content: 7.6% by mass, specific surface area: 264 m ² / g) was prepared and pulverized. Thereafter, it was dried at 400 ° C. for 3 hours as a pretreatment. Further, Tosoh one company manufactured NH ₄ peptidase old Lai Bok powder _{HSZ- 930 NHA (S i 0 2} / A 1 2 0 3 ratio: 27mo l / mo l, Na : 0. 02 wt ° / 0, after firing ratio Surface area: 630 m ² Zg, crystallite size: 0.02 to 0.04 m, particle size: 3 to 6) was also calcined at 650 ° C for 3 hours to obtain a proton type adsorbent.

[Adsorption desulfurization performance 1]

For the various adsorbents prepared in this example, the adsorption capacity of DBT was measured using a toluene solution containing 10 wt% of dibenzothiaphen (DBT) as a sample assuming a gas oil fraction. Here, DBT (manufactured by Tokyo Chemical Industry Co., Ltd., special grade dibenzothienephene) was included in the toluene solution. 10.Dip 1.0 g of each adsorbent into 4.0 g of a 10 wt% DBT / toluene solution at room temperature for at least 24 hours, and measure the sulfur compound content before and after soaking by gas chromatography to determine the adsorption capacity. It was measured. Since DBT and toluene are competitively adsorbed to the adsorbent, this sample solution is more severe for each adsorbent than the actual gas oil fraction with an aromatic content of 30 wt% or less. The results are shown in Table 1. As is clear from Table 1, it was found that the adsorptive desulfurization performance of the fibrous activated carbons A and B and the powdered non-activated carbon was superior to the adsorbents such as Zelite, silica gel and alumina. Moreover, absorption Chakuyoryo is larger than powdered raw active carbon Da rco KB towards the specific surface area 1 500m ² / g fibrous activated carbon B having a specific surface area of about 1 000m ² / g, from powdered activated carbon, activated carbon fiber It was found that the adsorbent had better adsorption desulfurization performance.

table 1

[Adsorption desulfurization performance 2]

Among the various adsorbents prepared in the above adsorption desulfurization performance 1, fibrous activated carbon A, fibrous activated carbon B, Zelite Lite HSZ-320 NAA, Zelite Lite HSZ-331 HSA, Zelite Lite Adsorption and desulfurization performance was evaluated for F-9 and Zelite Lite HSZ-930 NHA using actual light oil. Pre ultradeep sulfur concentration was determined desulfurized gas oil A (sulfur: 37 p pm) and ultra-deep desulfurization gas oil B (sulfur: 30 p pm) 20. to 0 g, respectively were, the adsorbent 3.0 ₉ Was immersed at room temperature for 24 hours or more, and the sulfur concentration after immersion was measured. The results are shown in Table 2. As is clear from Table 2, it was found that the adsorptive desulfurization performance of the fibrous activated carbons A and B was superior to the Zelite light. The sulfur concentration was measured by X-ray fluorescence analysis, and the sulfur concentration before and after immersion is expressed as the sulfur content obtained by converting the concentration of sulfur compounds contained in light oil into sulfur weight (the same applies hereinafter). Table 2

[Adsorption desulfurization performance 3]

 Among the various adsorbents prepared in the above adsorption desulfurization performance 1, fibrous activated carbon A, Zelite Lite HSZ-320 NAA, Zelite Lite HSZ-331 HSA, Zelite Lite F-9, and Zelite Lite We evaluated the adsorptive desulfurization performance of gasoline base material for Light HSZ-930N HA. Catalytic cracking (FCC) gasoline whose sulfur concentration was measured in advance (sulfur content: 62 ppm) 40. Og was immersed in each adsorbent 6. Og for more than 24 hours at room temperature, and the FCC gasoline after immersion The sulfur concentration was measured. The results are shown in Table 3. As is evident from Table 3, it was found that the adsorptive desulfurization performance of the fibrous activated carbon A was superior to that of Zesai Light. Table 3

[Desorption regeneration of activated carbon]

After using fibrous activated carbon A as an adsorbent in the above-mentioned adsorptive desulfurization performance 1, the fibrous Charcoal A was heated to 500 ° C at a rate of 100 ° C / hr under a nitrogen atmosphere and heated at 50 ° C for 2 hours. After cooling, the same experiment as in the adsorption desulfurization performance 1 was performed. The adsorption capacity was 84 (g-S / kg-adsorbent), and regeneration of the adsorbent was confirmed. Example 2

、 そして、 Sm i c r o X 2 xV ex t/S ex tは 4. 3 cm³/ gであった o 吸着剤 Cとして繊維状活性炭を用いた。 吸着剤 Cにおける S aは 2090m²/ g V i1 . 04 cm ³/g Daは 20A SrrH c r oは 2071 m²/g Vmi c c i1 . 01 cm³/g S ex tは 1 9m²Z9 Vextは 0. 0 3 cm³/g、 そして、 Sm i c r ox 2 xV e x t/S e x tは 9. 2 cm³/ gであった。 吸着剤 Cは繊維状のままで使用した。 吸着剤 Dとして繊維状活性炭（ュニチカ社製 W— 1 5W)を用いた。吸着剤 に おける S aは 1 390m ²/g Vaは 1 . 30 cm ³/g Daは 37 & Sm i c r

. 26 cm³/g S exは 21 m²/g Vex tは 0. 04 cm ³/g、 そして、 S m i c r ox 2xVe x t /S ex tは 4. 6 cm ³Zgであった。 吸着剤 Dは繊維状のままで使用した。 吸着剤 Eとして繊維状活性炭（クラレケミカル社製 F R— 1 5)を用いた。吸着 剤 Eにおける S aは 1 51 5m²/g Vaは 0. 54 cm ³Zg Daは 1 4A S m i c r oは 1 51 3 m²/g V m i c r oは 0. 54 c m³/g S e x t は 1 m ²/ g Vex tは 0. O O l S

そして、 Smi c r o x 2 x Vex t/S e x tは 3. 7 cm³/gであった。 吸着剤 Eは繊維状のままで使用 し 7 o 吸着剤 Fとして繊維状活性炭（クラレケミカル社製 F R— 20)を用いた。吸着 剤「における S aは 2454m²/g Vaは 0. 86 cm ³/g Daは 1 4A Sm"i c r G 2445m²Zg Vm i c r c^ O. 85 cm ³/g S ex t は 8m ²/ g Vex tは 0. 01 cm³/g、 そして、 S m i c r ox 2 xV e x t/S e x tは 7. 4 cm³/gであった。吸着剤 Fは繊維状のままで使用した。 吸着剤 Gとして繊維状活性炭（クラレケミカル社製 F R— 20)を用いた。吸着 剤 Gにおける Saは 2294m²/g Vaは 0. 81 cm³/g Daは 1 4A Sm i c r ( i2285m²Zg Vmi c iO. 80 cm ³/g S e x t は 9m ²/ g Vex tは 0. 01 cm³/g、 そして、 Smi c r ox 2xV e x t/S e x tは 7. 0 cm³/gであった。吸着剤 Gは繊維状のままで使用した。 吸着剤 Hとして繊維状活性炭（クラレケミカル社製 F R— 25 )を用いた。吸着 剤 Hにおける S aは 2749m²/g、 Vaは 0. 96 cm ³/g、 Daは 1 4A、 Smi c r c^ 2741 m²/g、 Vm i c r c^ O. 94 cm ³/g、 S ex t は 8m²/g、 Vex tは 0. 01 cm³/g、 そして、 Sm~i c r ox 2xVe x t/S e x tは 8. 8 cm³/gであった。吸着剤 Hは繊維状のままで使用した。 吸着剤 Iとして繊維状活性炭（柬邦レーヨン F E— 620— 7)を用いた。吸着 剤 Iにおける S aは 1 91 6m²/g、 Vaは0. 66 0171³/9、 0&は1 4&、 Sm i c r oは 1 91 3m²/g、 Vm i c r oは 0. 66 cm ³/g、 S ex t は 3 m²/g、 Vex tは 0. 01 cm³/g、 そして、 Smi c r ox 2 xVe x tZS ex tは 6. 6 cm³/gであった。吸着剤 Iは繊維状のままで使用した。 吸着剤 Jとしてフェルト状の繊維状活性炭（クラレケミカル社製 FT300— 2 0) を用いた。 吸着剤 Jにおける S aは 21 1 9m²/g、 Va ：は 0. 75 cm ³/g、 Daは 1 4A、 Sm i c r oは 21 1 5m ²/g、 Vm i c r oは 0. 7 5 c m³/g、 S ex tは 3 m²/g、 Vex tは 0. 01 cm³/g、 そして、 S mi c r ox 2xVex t/S ex tは 7. 6 cm³/gであった。 吸着剤 Kとして粉未状の活性炭を使用した。 吸着剤 Kにおける S aは 996 m² /g、 Vaは 0. 35 cm ³/g、 Daは 1 4A、 Smi c r c^ g s gmSZgs Vm i c r oは 0. S A

01 cm³/g、 そして、 S m i c r o x 2 x V e x t/S e x tは 3. 3 c m³/g であった。 吸着剤しとして粉末状の活性炭 （関西熱化学社製マックスソープ MSC— 30) を用いた。 吸着剤 Lにおける S aは 3305m²/g、 Vaは 1 · 67 cm ³/g、 Daは 20A、 Smi c r oは 3264m²/g、 Vm i c r oは 1. 60 cm³ /g、 S e x tは 42m²/g、 Vex tは 0. 07 cm³/g、 そして、 Sm i c r o x 2 X V e x t/S e x tは 1 1. 3 cm³Zgであった。 吸着剤 Mとして粉末状の活性炭を使用した。吸着剤 Mにおける S aは 2264 m ²/g、 Vaは 0. 80 cm ³/g、 Daは 1 4A、 Sm i c r oは 2260m²/ g、 Vm i c r oは 0. 79 cm³/g、 S ex tは 4m²/g、 Vex tは 0. 01 cm ³/ g、 そして、 Smi c r o x 2xVex t/S ex tは 7. 7 cm³ / gであった。 吸着剤 Nとして繊維状活性炭（クラレケミカル社製 F R— 1 0 ) を用いた。吸着 剤 Nにおける S aは 1 1 01 m²/g、 Vaは 0. 39 cm ³/g、 Daは 1 4A、 Sm i c r c^ 1 090m²/g、 Vm i c r c i0. 39 cm ³Zg、 S ex t は 1 1 m²/g、 Ve x tは 0· 00 cm ³/g、 そして、 Sm i c r o x 2 x V ex t/S ex tは 0. 0 cm³Zgであった。 吸着剤 Nは繊維状のままで使用し た。 前処理として、上記吸着剤 A〜Nを 1 50°Cで 3時間乾燥した後、各吸着剤 1. 0 gを、 軽油 （硫黄濃度 370 p pm、 密度 0. 8421 g/m 1 (1 5°C)、 窒 素分 （窒素化合物中の窒素換算重量） 1 0 p pm、沸点範囲 1 93. 5〜361. 5°C、 1 0%留出温度 270. 0°C、 90%留出温度 343. 5°C) 20. 0 gに、 1 0°Cで 24時間以上浸せきして、浸せき後の硫黄濃度を測定して吸着容量を求め た。なお、 ここで用いた軽油は原料軽油を予め水素化精製することにより得た。 S mi c r ox 2 xVex t/S e x tと吸着容量との関係を図 4に示した。図 4か ら明らかなように、 Smi c r ox 2 xVex t/S e x tが大きいほど吸着容量 が大きいことが分かった。この結果より、発明者が見出した脱硫吸着パラメータで ある Sm i c「 o x 2 xVex t/S e x tが硫黄分吸着量を決定付けているこ とが分かる。特に、 S m i c r o X 2 X V e X t/S e X tの値が 3. 0 cm³/ g以上の場合、吸着容量が 2. 0 g— S/k g— d「 y ad s o r be n t以上 となり、 特に Sm i c r ox 2xVex t/S e x tの値が 5. 0 cm³/g以上 で吸着容量が 2. 5 g-S/k g-d r y a d s o r b e n tを超えており、優 れた脱硫吸着性能を有する吸着剤になり得ることが分かった。 実施例 3 In Example 2, 13 types of adsorbents A to M shown below were prepared, and the adsorbing capacities of sulfur in light oil by the adsorbents were determined. For comparison, prepared adsorbent N Maikuropo § external pore volume Vex t is 0 cm _^3/9, was determined adsorption capacity under the same conditions. However, the parameters S ext of the adsorbents A to N described later are the micropore external specific surface area [m ² / g], Vext is the micropore external pore volume [cm ³ Zg], and S micro is the micropore specific surface area. ! ! ^ Micro], V micro is microphone pore volume [cm ³ Zg], D is density conversion coefficient (0.001 547 when nitrogen is used as gas) [cm ³ 1 q / cm ³ (STP)], Sa is Total specific surface area [m ² / g], Va is total pore volume [cm ³ / g], and Da is average pore diameter. Each parameter was determined using the measurement results of the nitrogen adsorption method and the above equations (2) to (8). Powdered fibrous activated carbon was used as adsorbent A. Sa in the adsorbent A is 266 9m ² / g, V a is ^{1. 36 cm 3 / g,} Da is 20A, Sm icro is 2630 m ² / g, Vm icro is ^{1 · 29 cm 3 / g,} S ext is 40 m ² / g, Vex t: 0.07 cm ³ / g, and Smicro X 2 xVext / S ext was 9.2 cm ³ / g. Powdered fibrous activated carbon was used as adsorbent B. S a in the adsorbent B is ^{1 1 5 5m 2 / g,} V a is ^{0. 44 cm 3 / g, D} a is 1 5 A, S micro is ^{1 1 37 m 2 / g,} Vm icro is 0.40 cm ³ / g, Sex is 18 m ² / g, Vex t is 0.03

The value of Micro X 2 xV ext / S ext was 4.3 cm ³ / g. O Fibrous activated carbon was used as adsorbent C. Sa in adsorbent C is 2090 m ² / g V i1 .04 cm ³ / g Da is 20A SrrH cro is 2071 m ² / g Vmi cc i1.01 cm ³ / g Sex is 19 m ² Z9 Vext is 0.03 cm ³ / g, and Smicr ox 2 xV ext / S ext was 9.2 cm ³ / g. The adsorbent C was used in a fibrous state. As the adsorbent D, fibrous activated carbon (W-15 W manufactured by Unitika Ltd.) was used. In the adsorbent, Sa is 1 390 m ² / g Va is 1.30 cm ³ / g Da is 37 & Sm icr

26 cm ³ / g Sex was 21 m ² / g Vex t was 0.04 cm ³ / g, and S microx 2xVe xt / S ex was 4.6 cm ³ Zg. Adsorbent D was used as it was in a fibrous state. Fibrous activated carbon (FR-15, manufactured by Kuraray Chemical Co., Ltd.) was used as the adsorbent E. In the adsorbent E, Sa is 155 5 m ² / g Va is 0.54 cm ³ Zg Da is 14A S micro is 151 3 m ² / g V micro is 0.54 cm ³ / g S ext is 1 m ² / g Vex t is 0.OO l S

And Smi crox 2 x Vex t / S ext was 3.7 cm ³ / g. The adsorbent E was used in the form of fibrous material, and 7 o fibrous activated carbon (FR-20 manufactured by Kuraray Chemical Co.) was used as the adsorbent F. In the adsorbent “S a is 2454 m ² / g Va is 0.86 cm ³ / g Da is 14A Sm” icr G 2445m ² Zg Vm icrc ^ O. 85 cm ³ / g Sex is 8 m ² / g Vex t was 0.01 cm ³ / g, and S micr ox 2 xV ext / S ext was 7.4 cm ³ / g. Adsorbent F was used as it was in a fibrous state. Fibrous activated carbon (FR-20 manufactured by Kuraray Chemical Co., Ltd.) was used as the adsorbent G. In adsorbent G, Sa is 2294 m ² / g Va is 0.81 cm ³ / g Da is 14A Sm icr (i2285m ² Zg Vmic iO.80 cm ³ / g Sext is 9 m ² / g Vex is 0. 01 cm ³ / g, and Smicrox 2xV ext / S ext was 7.0 cm ³ / g, and the adsorbent G was used in a fibrous state. As the adsorbent H, fibrous activated carbon (FR-25 manufactured by Kuraray Chemical Co., Ltd.) was used. In the adsorbent H, Sa is 2749 m ² / g, Va is 0.96 cm ³ / g, Da is 14 A, Smi crc ^ 2741 m ² / g, Vmicrc ^ O. 94 cm ³ / g, Sext Was 8 m ² / g, Vex t was 0.01 cm ³ / g, and Sm ~ icrox 2xVext / S ext was 8.8 cm ³ / g. The adsorbent H was used in a fibrous state. As the adsorbent I, a fibrous activated carbon (Choho Rayon FE-620-7) was used. S a in the adsorbent I is 1 91 6m ² / g, Va is 0.66 0171 ^3/9, 0 & is 1 4 &, Sm icro is ^{1 91 3m 2 / g, Vm} icro is 0.66 cm ³ / g, S ext was 3 m ² / g, V ext was 0.01 cm ³ / g, and Smi cr ox 2 xV e x tZS ext was 6.6 cm ³ / g. Adsorbent I was used in a fibrous state. As the adsorbent J, felt-like fibrous activated carbon (FT300-20 manufactured by Kuraray Chemical Co., Ltd.) was used. In the adsorbent J, Sa is 21 19 m ² / g, Va is 0.75 cm ³ / g, Da is 14 A, S micro is 21 15 m ² / g, V micro is 0.75 cm ³ / g. g, S ex t is 3 m ² / g, Vex t is 0. 01 cm ³ / g and,, S mi cr ox 2xVex t / S ex t was 7. 6 cm ³ / g. Activated carbon in the form of powder was used as the adsorbent K. Sa in the adsorbent K is 996 m ² / g, Va is 0.35 cm ³ / g, Da is 14 A, Smi crc ^ gs gm SZgs Vm icro is 0. SA

01 cm ³ / g, and S microx 2 x V ext / S ext was 3.3 cm ³ / g. Powdered activated carbon (Max Soap MSC-30 manufactured by Kansai Thermochemical Co., Ltd.) was used as the adsorbent. In the adsorbent L, Sa is 3305 m ² / g, Va is 167 cm ³ / g, Da is 20 A, Smicro is 3264 m ² / g, Vmicro is 1.60 cm ³ / g, and Sext is 42 m ² / g, Vex t is 0.07 cm ³ / g, and Sm i crox 2 XV ext / S ext was 11.3 cm ³ Zg. Activated carbon in powder form was used as adsorbent M. In the adsorbent M, Sa is 2264 m ² / g, Va is 0.80 cm ³ / g, Da is 14 A, S micro is 2260 m ² / g, V micro is 0.79 cm ³ / g, S ex t Was 4 m ² / g, Vex t was 0.01 cm ³ / g, and Smi crox 2xVex t / S ex was 7.7 cm ³ / g. As the adsorbent N, fibrous activated carbon (FR-10 manufactured by Kuraray Chemical Co., Ltd.) was used. S a in the adsorbent N is ^{1 1 01 m 2 / g,} Va is 0. 39 cm ³ / g, Da is 1 4A, Sm icrc ^ 1 090m 2 / g, Vm icrc i0. 39 cm 3 Zg, S ex t is ^{1 1 m 2 / g, Ve} xt is 0 · 00 cm ³ / g, and, Sm icrox 2 x V ex t / S ex t was 0. 0 cm ³ Zg. The adsorbent N was used as it was in a fibrous state. As a pretreatment, after drying the above adsorbents A to N at 150 ° C for 3 hours, 1.0 g of each adsorbent is added to light oil (sulfur concentration 370 ppm, density 0.8421 g / m 1 (15 ° C), Nitrogen content (weight in terms of nitrogen in nitrogen compounds) 10 ppm, boiling range 193.5 to 361.5 ° C, 10% distillation temperature 270.0 ° C, 90% distillation (Temperature: 343.5 ° C) The sample was immersed in 20.0 g at 10 ° C for 24 hours or more, and the sulfur concentration after immersion was measured to determine the adsorption capacity. The gas oil used here was obtained by previously hydrorefining the material gas oil. FIG. 4 shows the relationship between S microx 2 xVex t / S ext and the adsorption capacity. As is clear from FIG. 4, it was found that the larger the Smicrox2xVext / Sext, the larger the adsorption capacity. From these results, it can be seen that the desulfurization adsorption parameter found by the inventor, Smic “ox 2 xVext / Sext, determines the amount of sulfur adsorbed. In particular, SmicroX2XVeXt / When the value of S e X t is 3.0 cm ³ / g or more, the adsorption capacity becomes 2.0 g—S / kg—d “y ad sor bent or more, especially for Sm icrox 2xVex t / S ext. If the value is 5.0 cm ³ / g or more, the adsorption capacity exceeds 2.5 gS / kg dryadsorbent, It has been found that it can be an adsorbent having improved desulfurization adsorption performance. Example 3

In Example 3, the adsorbent H prepared in Example 2 was used as the adsorbent. First, the adsorbent was dried at 150 ° C for 3 hours, and then 19.6 g of the adsorbent was filled in an adsorption tower (hereinafter, referred to as a column) having a length of 600 mm and an internal volume of 54 ml. After filling the adsorbent, the column contains light oil (sulfur concentration 38 ppm, density 0.8377 g / ml (15 ° C), nitrogen 0.6 ppm, boiling point 206.0-367.0 ° C, a 10% distillation temperature of 271.0 ° C and a 90% distillation temperature of 347.5 ° C) flowed at 2 m 1 / min. At that time, the concentration of gas oil and the sulfur content in gas oil with respect to the cumulative amount of gas oil flowing out from the column were measured, and the changes are shown in Fig. 5. The sulfur content was measured by X-ray fluorescence analysis. However, the left vertical axis in FIG. 5 shows the concentration of the gas oil, and _c the right vertical axis represents the concentration of sulfur, cumulative effluent volume on the horizontal axis in FIG. 5 to the volume of the adsorbent It means the percentage of the effluent from the power ram. As shown in Fig. 5, the initial sulfur concentration was as low as 5 ppm, indicating that the sulfur was sufficiently adsorbed on the adsorbent. When the amount of adsorption was determined from FIG. 5, the amount of adsorption was 26 mg. Here, the adsorption amount was determined from Fig. 5 by integrating the amount of reduction in the sulfur content of the gas oil flowing out of the column with respect to the sulfur content of the gas oil flowing through the column. The accumulated effluent up to 3.3 ml / ml-ad sorbents was used as adsorption desulfurized gas oil. Then, n-decane was passed through the column at 2 ml / min. At that time, the concentration of light oil, the concentration of n-decane, and the sulfur content in the mixed solution were measured with respect to the cumulative amount of the mixed solution flowing out of the column, and the changes were shown in Fig. 6. However, the vertical axis on the left side of FIG. 6 represents the concentration of gas oil and n-decane, and the vertical axis on the right side represents the concentration of sulfur. As shown in Fig. 6, as the distribution of n-decane progressed, the amount of gas oil spill decreased, and finally the concentration decreased to near zero. In other words, it can be seen that the gas oil accumulated in the column almost flows out when n-decane flows through the column. Further, the desorption amount of the sulfur compound obtained from FIG. 6 was lower than the measurement accuracy (1 mg), and the sulfur compound was not desorbed. Here, the amount of sulfur compound desorbed from the column It was determined by integrating the sulfur content in the effluent. Next, toluene (desorbing agent) heated to 100 ° C. was passed through the column at 2 m 1 / min. At that time, the concentration of desorbent with respect to the accumulated outflow amount of mixture flowing out of the column, n- decane measured sulfur content in the concentration and mixture, _c but shown in FIG. 7 the change, in FIG. 7 The vertical axis on the left shows the concentration of the desorbent and n-decane, and the vertical axis on the right shows the sulfur content. As shown in Fig. 7, when toluene is passed through the column as a desorbent, the outflow of sulfur initially increases. However, it peaked at a certain cumulative runoff, after which the sulfur runoff decreased and eventually reached a sulfur concentration of less than 1 Oppm. That is, it can be seen that when toluene is passed through the column, the sulfur compounds adsorbed in the column are eluted. The amount of sulfur desorbed from Fig. 7 was 22 mg. From this value, it was found that the adsorbent in the column was almost completely desorbed and regenerated. Next, n-decane was again passed through the column at 2 ml / min, and then light oil was passed through the column at 2 ml / min. At that time, the concentration of light oil, the concentration of n-decane, and the sulfur content in the mixed solution with respect to the cumulative amount of the mixed solution flowing out of the column were measured, and the changes were shown in FIG. For comparison, the change in sulfur content during the first gas oil distribution is also shown in Figure 8. However, the vertical axis on the left side of FIG. 8 represents the concentration of light oil and n-decane, and the vertical axis on the right side represents the concentration of sulfur. As shown in Fig. 8, the change in sulfur content relative to the accumulated runoff was almost the same for the first and second runs. This indicates that the adsorption characteristics of the adsorptive desulfurizing agent in the first and second times are almost the same. Therefore, it can be seen that the adsorbent in the column was almost completely regenerated by the desorption regeneration step shown in FIG. Next, the types and concentrations of the sulfur compounds contained in the raw gas oil used in this example and the adsorptive desulfurized gas oil obtained in the above adsorptive desulfurization step were determined by gas chromatography-chemiluminescence, sulfur, detector (GC manufactured by Shimadzu Corporation). — SCD (G as C hro ma tograph—C he em il umi nescence S ulfur D etector), column: analysis using SUPELC® SPB 10.25 mm × 100 m). The results are shown in FIG. As is evident from Fig. 9, 4,6-DMDBT, which is the most abundant sulfur compound in feed gas oil, was hardly detected in adsorptive desulfurized gas oil. That is, it was found that the gas oil production method of this example can selectively remove 4,6-DMDBT, which is a hardly-desulfurized compound. Table 4 summarizes the properties and composition of the raw gas oil used in this example and the adsorptive desulfurized gas oil produced in this example. Table 4 also shows the properties and composition of hydrorefined gas oil for comparison.

Four

表 4から明らかなように、 この例で製造された吸着脱硫軽油は、水素化精製油に 比べて、芳香族分、特に 2環以上の芳香族分が低減している。特に、全芳香族分の 重量は原料軽油に比べてそれ程低下していないにもかかわらず、全芳香族分に対す る 2環以上及び 3環以上の芳香族分の割合が著しく低下していることに注目すベ きである。 また、軽油の色については、水素化精製軽油に比べて著しく向上してい ることが分かる （+30以上）。 さらに全硫黄分に対する 4， 6— DMD BTの硫 黄化合物の割合が 3%と極めて低い値となっており、 この例で用いた吸着剤は、 4, 6-DMD B Tを選択的に吸着することができることが分かった。また、 90%留 出点を比較すると、表 4から明らかなように、原油軽油の 347. 5°Cに対して、 吸着脱硫後の軽油は 347. 0°Cとなり、 ほぼ原料軽油と同じ値となった。すなわ ち、 この例で用いた吸着脱硫による軽油の製造方法では、軽油に含まれる硫黄分を 低減させながらも、軽油自身の特性を変化させることなく軽油を製造することが可 能であることが分かった。 実施例 4

As is clear from Table 4, the adsorptive desulfurized gas oil produced in this example has a reduced aromatic content, particularly an aromatic content of two or more rings, as compared with the hydrorefined oil. In particular, although the weight of total aromatics is not much lower than that of light diesel oil, the proportion of aromatics with two or more rings and three or more rings with respect to the total aromatics is significantly reduced. It should be noted that: In addition, it can be seen that the color of light oil is significantly improved compared to hydrorefined light oil (+30 or more). Furthermore, the ratio of the sulfur compound of 4,6-DMD BT to the total sulfur content is extremely low at 3%, and the adsorbent used in this example selectively adsorbs 4, 6-DMD BT. I found that I could do it. Comparing the 90% distillation points, as can be seen from Table 4, the gas oil after adsorptive desulfurization is 347.0 ° C, compared to 347.5 ° C for crude gas oil, which is almost the same value as the raw gas oil. It became. In other words, the gas oil production method using adsorptive desulfurization used in this example is capable of producing gas oil without changing the characteristics of the gas oil itself, while reducing the sulfur content in the gas oil. I understood. Example 4

In Example 4, the adsorbent J prepared in Example 2 was used as the adsorbent. As a pretreatment, the adsorbent was dried at 150 ° C for 3 hours, and two columns having a length of 60 Omm and an inner volume of 54 ml were filled with a total of 17.3 g of the adsorbent. Gas oil (sulfur concentration 38 ppm, density 0.8377 g / ml (15 ° C), nitrogen content 0.6 ppm, boiling point 206.0-367.0 ° C, 10% distillate temperature: 271.0 ° C, 90% distillate temperature: 347.5 ° C) at 2 m 1 / min. Thereafter, the temperature of the column was increased from room temperature to 160 ° C, and nitrogen gas was supplied to the column at a pressure of 1.5 kgf / cm ² G (0.15 MPa aG) at a flow rate of 3 ml / min, The gas oil inside the column was discharged and recovered by the pressure of nitrogen gas. The recovered amount of gas oil was 7 Om 1. Then, toluene was passed through the column at 2mΊ / min. The concentration of light oil in the toluene flowing out of the column indicated that the amount of light oil remaining in the column was 11 m "!. Then, the temperature of the column was reduced from room temperature to 160 ° C. Heat and apply nitrogen gas at a pressure of 1.5 kgf / cm ² G (0.15 MPaG) at a flow rate of 3 ml / min. The solution was supplied to the ram and the toluene inside the column was allowed to flow out and collected by the pressure of nitrogen gas. The recovered amount of toluene was 74 ml. After toluene recovery, light oil was passed through the column again. From the concentration of toluene contained in the gas oil flowing out of the column, it was found that the amount of toluene remaining in the column was 1 O ml. As described above, it was confirmed that about 90% of the liquid in the column could be recovered by the pressure of nitrogen gas. Example 5

 [Immersion adsorption experiment of fuel oil]

 Zesai Light HSZ-320 NAA prepared in Example 1, Zesai Light F-9, fibrous activated carbon H, Zesai Light HSZ-320 NAA and fibrous activated carbon H of 50 mass %: 50% by mass and fibrous activated carbon H mixed at a ratio of 50% by mass: 50% by mass with adsorption and desulfurization of gasoline base materials The performance was evaluated. FCC gasoline (aromatic content: 21% by weight, total sulfur content: 31 ppm, density 0.72 83 g / m @@ 15 ° C, nitrogen content 1 O ppm, boiling point range 33.5-2 12.0 ° C), immerse the adsorbent in FCC gasoline: adsorbent = 20 g: 2 g at 24 ° C for more than 24 hours, and measure the sulfur concentration of the fuel oil before and after immersion did. Tables 5 and 6 show the sulfur concentration after immersion. 100% by mass zeolite F-9: 50% by mass zeolite F-9 + 50% by mass fibrous activated carbon H: 100% by mass zeolite HSZ — 50% by mass zeolites HSZ—32% AA + 50% by mass fibrous activated carbon H showed a lower sulfur concentration than that of NAA, indicating that the fibrous activated carbon was lower. The validity of the combination with can be confirmed. Table 5

 Adsorbent type F C C Sulfur content of gasoline (relative value)

100% by mass zelite light HSZ- 320NAA 100

 100% by mass fibrous activated carbon H60

 50% by mass ZEISHITE LIGHT HSZ—320NAA 66

+ 50% by mass fibrous activated carbon H Table 6

Industrial applicability

 According to the gas oil production method of the present invention, after adsorbing and desulfurizing sulfur contained in gas oil, the adsorbent can be desorbed and regenerated and used again for adsorptive desulfurization. The sulfur content can be sufficiently removed over a long period of time at operating costs. Further, according to the gas oil production method of the present invention, a sulfur compound and a polycyclic aromatic (two or more rings) are selectively removed by using a carbon material, particularly a fibrous activated carbon, as an adsorptive desulfurizing agent. Therefore, more environmentally friendly light oil can be provided. Furthermore, the method for producing gas oil of the present invention can selectively reduce DBTs, particularly 4,6-DMDBT, which are difficult to desulfurize by hydrorefining. By combining these, it is possible to purify diesel oil with a sulfur concentration of 10 ppm or less, and even with a sulfur concentration of 1 ppm or less. Further, since the 90% distillation point of the adsorptive desulfurized gas oil obtained by the gas oil production method of the present invention is almost the same as that of the raw gas oil, the sulfur oil contained in the gas oil is used in the gas oil production method of the present invention. It is possible to produce light oil without changing the characteristics of light oil itself while reducing the amount.

Claims

The scope of the claims 1. Adsorption desulfurization agent, An adsorptive desulfurizing agent containing a carbon material having a specific surface area of 500 m ² / g or more and adsorbing organic sulfur compounds contained in a petroleum fraction. 2. The adsorptive desulfurizing agent according to claim 1, wherein the carbon material is a fibrous activated carbon having a specific surface area of 2000 m ² / g or more and an average length of 1 OOm or more. 3. micropore specific surface area Sm Icro of the carbon material (m ² Zg), Maikuropo § external pore volume Vex t (0171 ³ da 9) and Maikuropoa external specific surface area ^{3 e X t (m 2 /} g) is the following formula:  Smi crox 2xVex t / S ex t> 3.0 2. The adsorptive desulfurizing agent according to claim 1, which satisfies the following. 4. The adsorptive desulfurizing agent according to claim 1, wherein the petroleum fraction is a gasoline fraction and further contains a zeolite component. 5. A desulfurization method for petroleum fractions, A method for desulfurizing a petroleum fraction, comprising a step of bringing an adsorptive desulfurization agent containing a carbon material having a specific surface area of 500 m ² / g or more into contact with a petroleum fraction containing an organic sulfur compound. 6. The organic sulfur compound contains 4,6-dimethyldibenzothienephene, and the petroleum fraction is brought into contact with the adsorption / desorption sulfuric agent so that the total sulfur content in the petroleum fraction is 4,6,1-dimethyldibenzothiene. The method for desulfurizing a petroleum fraction according to claim 5, wherein the proportion of fuene is reduced to 10% or less. 7. After performing the step of bringing the above-mentioned adsorptive desulfurizing agent into contact with the above-mentioned petroleum fraction, the above-mentioned adsorptive desulfurizing agent is heated in a non-oxidizing atmosphere to desorb organic sulfur compounds and to adsorb and desulfurize it. 6. The method for desulfurizing a petroleum fraction according to claim 5, comprising a step of regenerating the agent, and a step of contacting the regenerated adsorptive desulfurizing agent with a petroleum fraction containing an organic sulfur compound. 8. The adsorptive desulfurizing agent according to any one of claims 5 to 7, wherein the petroleum fraction is a gasoline fraction, and the adsorptive desulfurizing agent contains a zeolite component. 9. A method for producing light oil, Adsorption by bringing a gas oil fraction in a liquid phase having a sulfur content of 500 ppm or less into contact with an adsorptive desulfurizing agent containing a carbon material having a specific surface area of 500 m ² / g or more and adsorbing sulfur compounds contained in the gas oil fraction. Desulfurization process,  A desorption regeneration step of regenerating the adsorptive desulfurizing agent by washing with an aromatic solvent. 10. Further, before the adsorptive desulfurization step, a step of hydrorefining the raw gas oil is included, and the gas oil fraction in the liquid phase having a sulfur content of 500 ppm or less can be obtained by the hydrorefining step. 10. The method for producing light oil according to claim 9, wherein: ' 11. The method for producing gas oil according to claim 9 or 10, further comprising a step of recovering gas oil in the adsorptive desulfurization agent after the adsorption desulfurization step and before the desorption regeneration step. 12. The method for producing a gas oil according to claim 9 or 10, further comprising a step of removing a desorbing agent in the adsorptive desulfurizing agent after the desorption regeneration step and before the adsorptive desulfurization step. 1 3. The sulfur concentration is 15 ppm or less, the ratio of sulfur of 4,6-dimethyldibenzothienephen to the total sulfur is 10% or less, and the 90% distillation temperature is 310 ° C. Light oil that is more than. 1 4. Diesel oil with a sulfur concentration of 15 ppm or less, a ratio of two or more aromatics to total aromatics of 7% or less, and a 90% distillation temperature of 310 ° C or more. 1 5. Light oil whose sulfur concentration is 15 ppm or less, the ratio of tricyclic aromatics to total aromatics is less than 0.5%, and whose 90% distillation temperature is 310 ° C or more.